85d5ead Updated the concat function so that it wouldn't modify the
original array. A side-effect of this change is that it now always calls
`Array()` on the second argument. If thit is a Hash, this results in
`to_a` being called on the hash, which converts it to an array or
tuples. This is undesired.
Update the behaviour so that it doesn't (indirectly) call `to_a` on
anything, instead test for the type of the argument, wrapping it in an
array if it's not already an array.
44596e73da